It gives me much pleasure to introduce this work of Prof. Dr. Ing. Fumagalli, a work that covers both the development and present state of the art of structural model techniques. In my view, in this context, only a lack of understanding of the possibilities offered by experiments on models and sometimes an unjustified suspicion of them have up to now restricted the development that these methods deserve. I think, in particular, and the many examples quoted in the text bear witness to this, that models today constitute an efficient means of research that have been refined through advances in the methods of reproduction, testing and measurement. They represent a reliable and above all safe method of investigation, suitable for use in the elastic range and beyond up to failure, as much for historic ancient monuments as for modern works and structures of particularly bold design that are frequently highly redundant. They are a particularly valuable tool in areas where analytical methods are inadequate, and yet always useful for comparison with analytical results. Guido Oberti Preface I have embarked on writing a text on the techniques of structural models for two basic reasons: Firstly because I wish to attempt in some measure a personal appreciation of the subject based on more than twenty years experience, insofar as this can be achieved in a logically coherent and complete treatise.